Equipment that provides a high degree of reliability is a prime consideration of organizations that supply Internet and Intranet services. To help meet this need, technology has become available to combine several devices into a cluster that is configured to act as a single device. Using the cluster arrangement, it is intended that the failure of one device does not significantly affect the remaining components within the cluster.
The term for starting software on a device is ‘booting’ (short for ‘bootstrapping’); when this is performed on a device that is active, the term is ‘rebooting’. A reboot is normally performed for a variety of reasons, including: to activate new versions of the software; and to restore functionality of the device after a fatal error in the software that prevents the device's operation.
In a cluster environment, the reboot of devices requires special consideration, since maintenance of the cluster functionality is of utmost importance. Rebooting the cluster, however, may interfere with its operation. What is needed is a way to reboot members of a cluster such that the cluster operation is maintained.